Conventional microelectronic devices are employed in a vast number of consumer and industrial electronic products. Patterns that interconnect components used in these devices are typically formed by lithography processes. A conventional lithography process involves applying a resist to a silicon- containing wafer. A clear and opaque mask containing features that define the pattern to be created in the resist is then placed over the wafer, and the resist is subsequently exposed to light. The resist is then developed using a solution, and specified resist regions are etched to form a pattern in the wafer.
It may be desirable to manufacture microelectronic devices having smaller critical dimensions. In particular, wafers employed in these devices often have narrower line widths. As a result, more components (e.g., transistors) may be placed on the wafers, thus making microelectronic devices formed from these wafers potentially faster in operation and less expensive.
Manufacturing microelectronic devices having smaller critical dimensions, however, may present certain difficulties. For example, the performance of devices with resists having narrower and narrower line widths may become more adversely affected by resist surface roughness. Thus, it is expected that the roughness of a resist will make a substantially larger contribution to the error budget for the resist critical dimension. For example, if the error budget for a 100 nanometer (nm) line is plus or minus 7 percent, that is 7 nm, any roughness on the resist on the order of 7 nm would consume the entire error budget, thus potentially leaving little or no latitude for variations in processing. Moreover, resist surface roughness may be exacerbated due to the use of conventional resist developing solutions.
It is believed that the degree of resist roughness may be dependent upon the type of polymer used in the resist. For example, Yoshimura et al., Appl. Phys. Lett. 63 (6) 764-766 (1993) proposes that differences in polymer species utilized in the base resins which form the resists can result in differences in resist surface roughness.
In view of the above, it would be desirable to be able to reduce surface roughness by processing means. As a result, one could potentially control surface roughness independently of the type of polymer employed in the resist base resin. Moreover, it would be desirable to alleviate the potential adverse effects of developing solutions on resist surface roughness.